Shock-wave devices are commonly used clinically for therapeutic treatment. For example, an electrohydraulic shock-wave lithotripter is a device that generates a focused shock-wave and directs it onto a clinical target, such as a kidney stone. An electrohydraulic shock-wave lithotripter is only one example of the shock-wave devices that can benefit from the present invention. This device is characterized by a focusing reflector having spaced-apart first and second foci. A shock-wave generator is positioned substantially at the first foci and is adapted to discharge shock-wave creating energy outwardly from itself to the focusing reflector. The focusing reflector is configured to receive shock-wave energy and focus it and direct it as a focused wave to a target (e.g. kidney stone) at the second foci.
One use of a shock-wave focusing device is to fragment kidney stones into small pieces that can then be safely removed from a patient via the urinary tract. There is evidence that normal tissue can at the same time be damaged. Several thousand shock-wave generations are necessary to fragment a kidney stone. The clinician takes care to operate the lithotripter at the highest safe rate of operation. Currently, the instrument is operated typically at 0.5-2.0 Hz pulse repetition frequency (PRF). There is a need to decrease the total number of shock-waves that are delivered to the kidney stone to cause its comminution, in order to reduce the unwanted and unhealthy bioeffects on healthy tissue.
A principal object of the present invention is to increase the efficiency of a focused shock-wave device so that it can perform its function satisfactorily by use of a reduced number of focused shock-waves or by an increased PRF.